1. Field of the Invention
The subject invention relates to a flame retardant and a flame-retardant resin composition containing the flame retardant and its use.
2. Description of the Prior Art
Around us, there are many articles with a close connection to daily life which are made from flammable organic polymer materials, such as household electrical appliances, automated office equipment, electrical and electronic devices, building materials, automobile materials, etc. In order to improve quality of life and ensure safety, a way must be found to modify the properties of organic polymer materials, decrease the possibility of burning and thus decrease the frequency of fires by means of a flame retardant and flame retardant technology.
In general, organic polymer materials have poor flame retardancy. Therefore, the flame retardation of materials is the key to developing this technology, and the development and application of flame retardants are among the most crucial goals. There are various kinds of flame-retardants used in polymer materials. Depending on the presence or absence of halogen, flame retardants can be divided into two classes, i.e. halogen-containing flame retardants and halogen free flame retardants. Currently used halogen-containing flame retardants are mainly chlorine- and bromine-containing compounds. Halogen-containing flame retardants have considerable effect on flame retardancy, for example, brominated bisphenol-A epoxy resin, which can provide the effect of flame retardancy for the polymer materials when only added in a small amount. However, halogen-containing flame retardants can produce corrosive and toxic hydrogen halide gas, produce a large amount of fumes, and may be suspected of producing harmful cancer-inducing toxic gases, such as halogenated dioxin, halogenated furan, etc., when burnt. As a result, Restriction of Hazardous Substances (RoHS) in EEE has been regulated in the Directive on “Waste Electrical, Electronic Equipment (WEEE)” established by EU, wherein bromine containing compounds such as polybrominated biphenyl (PBB), polybrominated diphenyl ethers (PBDE), etc., have been clearly prohibited.
An environmentally-sensitive material free of halogen is defined as a material in which the chlorine content of the material as a whole is less than 900 ppm and the bromine content is less than 900 ppm which can be developed and used in an environmentally sensitive manner. At present, the material free of halogen is developed mainly according to the four concepts below: (1) the flame retardancy has to meet the requirement of the UL94-V0 standard; (2) the material is free of halogen; (3) the material is free of element stibium; and (4) the material is free of red phosphorus. Although stibium and red phosphorus are good substitutes for halogen as the flame retardant of epoxy resins, stibium has a risk of inducing cancer. In addition, flame retardants containing phosphorus groups have been disclosed presently in certain patents, such as U.S. Pat. No. 6,291,627 and Taiwan Patent Publication No. 490474, etc. However, although halogen-containing flame retardants can be effectively replaced by phosphorus flame retardants, the latter may result in eutrophicated rivers due to the hydrolyzation of phosphorus, which turns out to be another environmental problem. On the other hand, red phosphorus has the property of self-ignition and can easily cause danger. Therefore, stibium and red phosphorus have also become the chemicals to be avoided. To this end, the subject inventors provide a novel flame retardant, which can effectively avoid the problems described above.